Explosive-actuated well tool anchor



March 27, 1962 w. G. swEETMAN ExPLOsIvE-ACTUATED WELL TOOL ANCHOR 2Sheets-Sheet l Filed July 50, 1959 E W//cm (i fweeman ...VQMH fw C mi:

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INVENTOR.

ATTANEV March 27, 1962 w. G. SWEETMAN 3,026,939

EXPLOSIVE-ACTUATED WELL TOOL ANCHOR Filed July 30, 1959 2 Sheets-Sheet 2nited @rates arent l 3,026,939 Patented Mar. 27, 1962 tice 3,026,939EXPLSIVE-ACTUATED WELL T001. ANCHOR William G. Sweetman, McCullough ToolC0., PA). Box 2575, Houston, Tex.

Filed .llnly 30, 1959, Ser. No. 830,665 Claims. (Cl. 166-55) Thisinvention relates to improvements in anchors for well tools and moreparticularly to explosive-actuated anchors.

Devices for anchoring tools in well casings or other well pipes areactuated in various ways. Some employ mechanical means, such asscrew-actuated or weight-responsive wedges acting on wall grippingslips. Others employ hydraulic actuating means, and still others haveemployed anchoring apparatus which are actuated by the force of anexplosive charge to set them in the well wall.

' In the operation of various types of well tools, particularly wellperforators and chemical cutting tools, such as those described in myco-pending applications Serial No. 507,316, filed May 5, 1955, nowPatent No. 2,918,125, and Serial No. 735,875, filed May 16, 1958, it isof the utmost importance that the tool be positively and firmly anchoredagainst any vertical movement during performance of the cutting orperforating function of the tool. Chemical and explosive perforating orcutting necessarily produce strong reactive forces against the toolwhich tend to displace the tool longitudinally of the well bore unlessit is solidly anchored. uAny such longitudinal displacement of the tool,particularly during chemical cutting and perforating will result inimproper cuts and ineffective perforation and, therefore, must beavoided to the greatest extent possible.

l in my aforementioned co-pending applications, I have discloseddifferent arrangements by which a charge of an explosive is employed toactuate the wall-engaging anchors and to also actuate the chemicalcharge which effects the desired cutting and perforating action. Theseearlier arrangements have proven entirely successful but cases haveoccurred when even these anchoring arrangements have not anchored thetools as solidly as necessary for accomplishing the most eiiicientcutting and perforation.

The present invention, therefore, has for its primary object theprovision of an improved form of explosiveactuated anchor which obviatesthe diiiiculties encountered -with the earlier forms of such anchors.

An important object is the provision of an explosiveactuated anchormechanism for well tools wherein the explosive forces are concurrentlyemployed to 'actuate both the anchor mechanism and the well tools.

An additional object is the provision of an anchor mechanism forchemical well cutting tools wherein high pressure gases generated by theignition of explosive material is employed to actuate and set the anchormechanism, a portion of said gases being concurrently employed toactuate the cutting tool.

In accordance with the present invention, an arrangement is providedwherein two separate charges of eX- plosive are disposed in chamberspositioned above and below the anchoring elements. Passageways providecommunication between the chambers and the tool section carryingradially projectible anchor elements. A choke passage is provided in thelower end of the lower chamber. With this arrangement, the explosivecharge in the upper chamber, when set oli by a suitable initiator, willgenerate high pressure gases which will actuate the anchor elements andwill also set oti the explosive charge in the lower chamber. The gasesgenerated in the latter will, by reason of the restriction provided bythe choke passage at its lower end, supplement the expansive force ofthe gases generated by the rst explosive charge to intensify theprojecting force on the anchor elements, to thereby assure solidanchoring of the tool to the Well wall. Hot gases leaving the lowerchamber may then be applied to setting-off the perforating or cuttingcharges, whether of the chemical character described in theaforementioned applications, or of explosive form commonly used inbullet or shaped-charge perforators.

The pressurizing medium employed in actuating the anchor elements willbe gases generated by the ignition of one of the various types ofrelatively slow-burning gun powders, or other deflagrating types ofexplosives, examples of which are black powders such as used in sportingammunition, rocket propellant powders and the like. By appropriateselection of the explosive and by means of preparation procedures wellknown to those skilled in the art of such explosives, the ignition andburning rates may be eitectively controlled to generate gases at anydesired rate and volume suitable for apply ing the desired pressurizingforces both to the anchor elements and to the bodies of chemical uids inthe case of chemical cutters, or to other well tools which areactuatable by such pressurizing gases. The gases so generated will, ofcourse, be at high temperature, and their pressure and temperature willbe utilized to set oit bullet propellant charges or shaped-charges whichmay be employed in gun perforators, cutting devices, and the like,attached to the anchor sections of the tool. These gases may also beemployed to actuate other types of well tools such as bridging plugssuch as those disclosed in U.S. Patents 2,621,744, 2,651,371 and2,656,891.

Various other and more specific objects and advantages of this inventionwill become readily apparent from the following detailed descriptionwhen read in conjunction with the accompanying drawing.

In the drawing:

FIG. 1 is a generally diagrammatic view, partly in section, showing achemical cutting tool employing an anchoring apparatus in accordancewith this invention installed in a well;

FIGS. 2A, 2B and 2C, together, constitute a longitudinal sectional Viewof the anchoring section of the tool, taken generally along line 2 2 ofFIG. 1, showing the structural details thereof; and

FIG. 3 is a cross-sectional View taken along line 3 3 of FIG. 2B.

Referring first to FIG. 1, there is shown a cutting tool, designatedgenerally by the numeral 1, which is inserted in a string of tubing orother pipe 2, extending into a well bore B, which may be lined with theusual metal casing 3. The cutting tool comprises, in downwardly arrangedsuccession, an upper pressurizing section, designated generally by thenumeral 4, an anchor sub, designated generally by the numeral 5, a lowerpressurizing section, designated generally by the numeral 6, a chemicalcontainer section, designated generally by the numeral 7, an ignitersection designated generally by the numeral 3, and a discharge headsection, designated generally by the numeral 9. These several sections,which are constructed of suitable strong metal, such as steel, aregenerally cylindrical and connected together in end-to-end co-axialrelation to form an elongate cylindrical tool of substantially uniformexternal diameter, which is adapted for insertion into the tubingstring. A tiring head section, designated generally by the numeral 10,is connected to the upper end of the tool and is suitably secured to arope socket 11 of generally conventional form, which connects the upperend of the tool to a conventional iiexible cable 12 which is employedfor lowering and raising the tool in the well bore B. The cable 12 mayinclude electrical leads 13 for transmitting electric current from asuitable source (not shown) at 3 the surface to the interior of the toolfor purposes to be subsequently described.

The details of the portions of the chemical cutting tool underlyinglower pressurizing section 6 do not, of themselves, form a part of thepresent invention and will be referred to hereinafter only in a generalway in order to illustrate the relation of the anchor elements of thetool to the cutting tool.

Referring now FIGS. 2A, 2B, 2C and 3, inclusive, which illustrate thedetails of the explosive-actuated anchor elements of the tool, tiringhead section 10 (FIG. 2A) includes an electrically-fired, explosiveinitiator cap 14 of'known form mounted in a barrel 15. It will beunderstood that the cap 14 will be suitably connected to electricalleads 13. The cap, its supporting structure, and its connection to theleads 13 comprise conventional and well-known devices and their detailslikewise do not form a part of the present invention.

Upper pressurizing section 4 (FIGS. 2A and 2B) comprises a tubularmetallic body having an axial bore 17 extending entirely therethrough.The upper portion of bore 17 is adapted to receive barrel 15 and cap 14when head section 10 is made up with body 16. Bore 17, at a pointsomewhat below its upper end, is internally threaded at 18 to receive achoke plug 19 provided with an axial choke passage 20 registering withthe bore of barrel \15 and providing communication with the lowerportion of bore 17, which is herein sometimes referred to as the upperpressurizing chamber. Choke plug 19 is counterbored from its lower endto form a valve chamber 21 containing a ball check valve 22 adapted toengage a seat 23 in the upper end of chamber 21 to close oil chokepassage 20 against back-flow of pressure iiuid through the chokepassage. The lower end of chamber 21 is internally threaded at`24 toreceive a choke bushing 25 having an axial passage 26 therethrough.'I'he inner end of bushing 25 is provided with an upwardly extendingspider 27 which serves as a lower stop for ball check valve 22 to allowthe latter to move downwardly to its open position below seat 23, whileper-mitting ilow of gases through the spider into passage 26. The lowerend of body 16 is provided with an externally threaded pin 28 (FIG. 2B)adapted to be received in an internally threaded socket 29 formed in theupper portion of anchor sub 5.

Anchor sub 5 (FIG. 2B) comprises a generally cylindrical body 30 havinga plurality of longitudinal passages 31 (three shown, see FIG. 3) ofrelatively restricted diameter extending entirely therethrough andlaterally offset from the longitudinal axis thereof, the upper ends ofpassages 31 communicating with the interior of socket 29 and thence withthe interior of bore 17 in the pressurizing section. The lower ends ofpassages 31 communicate with the interior of an internally threadedsocket 32 formed at the lower end of body 30 and adapted for connectionto the succeeding sections of the tool.

'Body 30 is provided with a plurality of radially disposed, angularlyspaced cylinders 33, each communicating at its inner end with one of thepassages 31 and at its outer end with the exterior of body 30. The outerends of cylinders 33 are annularly enlarged to form seats 34 to receiveslip elements 35 having toothed outer faces 36 adapted to grippinglyengage the surrounding pipe wall when urged outwardly of body 30 againstthe pipe wall. Slip elements are mounted on the outer ends ofcylindrical Shanks 37 which are slidably disposed in cylinders 33 andfitted with circumferentially arranged seal rings 3S, such asconventional O-rings, whereby to for-m fluid-tight slidable sealsbetween shanks 37 and cylinders 33`l Spring retainers 39 are mounted onthe exterior of body 30 to resiliently hold the slip elements in placein cylinders 33 while permitting limited outward movement thereof.

Lowerpressurizing section 6 (FIGS. 2B and 2C) comprises a tubular body40 having an axial bore 4ltherethrough, what is sometimes hereinaftercalled the lower pressurizing chamber, communicating at its oppositeends with upper and lower externally threaded pin members 42 and 43,respectively. Upper pin member 42 is threadedly receivable in socket 32at the lower end of body 30 and pin member 43 is receivable in a socket44 provided in the upper end of chemical container section 7.

At its lower end bore 41 is internally threaded at 45 to receive anexternally threaded choke plug 46 having an axial choke passage 47extending therethrough, providing communication between bore 41 and theinterior of socket 44. The bore of the latter, for purposes ofillustration, is shown to be closed at its lower end by means of a sheardisk D held in place against the bottom of socket 44 by a tubularretainer bushing 48 which is screwed into socket 44 into clampingengagement with the shear disk. While this arrangement is employed wherechemical cutting tools are connected to the anchor elements, it will beunderstood that chemical container section 7 and the other elementsconnected to the lower end thereof may be replaced by bullet orshaped-charge perforators, or expansible plugs or the like, in whichcase, firing passages in the latter will be in open communication withthe discharge from choke passage 47.

Disposed in upper and lower pressurizing chambers 17 and 41 are bodiesof a suitable pressurizing medium (FIGS. 2A to 2C). 'I'he pressurizingmedium is preferably the same in each instance and comprises a body of arelatively slow-burning or deagrating explosive material 50 of thecharacter previously described. The body of the explosive may be inmolded cylindrical form, slightly smaller in diameter than the bores ofchambers 17 and 41 to allow free passage of gases about the explosivebody. The latter may also be supported by tubular spacer members 511disposed longitudinally in cham- Ibers 17 and 41. Spacer 51 in chamber17 has one end resting on the bottom of socket 29 and supporting thebody of explosive 50 on its upper end. Spacer member 51 in chamber 41has its lower end resting on the inner end of choke plug 46 and likewisesupporting its body of explosive 50 on its upper end. Spacer members 51serve to hold the explosive bodies away from the bottom of therespective chambers, and are provided with a plurality of openings 52 inthe wall thereof to permit free passage of gases formed by burning ofthe explosive bodies 50 `from the respective chambers into passages 31and choke passage 47, respectively. A small pellet of an igniterexplosive 53 may be positioned on the upper end of each of bodies 5t) toaccelerate the burning of the latter.

The above-described device is operated in the following manner: Chambers17 and 41 of the device will be charged with the bodies of explosivematerial 56 and the upper and lower pressurizing sections will beassembled with anchor sub 5. In the case of a chemical cutter theseportions of the apparatus will be assembled with chemical containersection 7, along with the several tool portions connected below thelatter, the parts being assembled in the arrangement schematicallyillustrated in FIG. l. The upper end of the tool will be connected tofiring head 10 and to rope socket 11. The structure will then be loweredinto the tubing to the point at which it is to be operated.

Electric current, from any suitable and conventional source (not shown)will then be applied to leads 13 to set off cap 14. Flame resulting fromignition of the cap will be discharged through choke passages 20 and 26into upper chamber 17 where it will cause successive ignition of pellet53 and explosive material 50. The gases generated by the burning ofexplosive material 50 in upper chamber 17 will flow through passages 31and exert pressure against the inner ends of shanks 37 of the slipmembers sutiicient to drive slips 35 outwardly into anchoring engagementwith the wall of tubing 2. The pressurizing gas ilowing through passages31 will enter the top of lower pressurizing chamber 41 and will thencause successive ignition of pellet 53 and body 50 contained in thischamber. The additional gases thus generated in the lower chamber will,by reason of the restriction formed by choke passage 47, supplement thepressure supplied from the upper pressurizing chamber to increase thedriving force on slip members 35, thereby assuring application ofsuicient pressure to the slips to securely and solidly anchor the toolto the pipe. Gases escaping through choke passage 47 will be operativeto actate the cutting and perforating elements of the tool as describedin my aforementioned applications. This anchoring action will occur inadvance of the discharge of the chemical fluids from the tool, or tiringof the explosive perforating or plug-expanding charges, as the case maybe, so that the tool will be held rmly against movement, andparticularly against upward thrust, resulting from the recoil orretractive action occurring in portions of the tool below the anchoringelements. So long as pressurizing lgases continue to discharge fromchamber 41, the slips will remain anchored to the pipe. As soon asexplosive material 50 has been consumed, or the internal pressureagainst the slips has been fully dissipated, retainer springs 39 willact on the outer end faces of slips 35 to urge them back into seats 34and release the tool from the pipe so that it may be withdrawn from thewell.

It will be understood that the internal pressure developed in upperchamber 17 will tact upon ball check valve 22 to move it to its closedposition on seat 23 and thereby act to prevent loss of pressure throughthe upper end of the chamber.

By way of example, a chemical cutting tool of the general characterillustrated, which was employed for severing two-inch well tubing,employed for i-ts anchoring elements upper and lower pressurizingsections and an anchor sub of the form and arrangement illustrated anddescribed herein. Each of the bodies of explosive 50 consisted of 500grains of a conventional rocket propellant powder molded into acylindrical stick 37A@ inches in length and inch in diameter. Igniterpellets 53 consisted of grains of a conventional readily ignitablepowder formed into a cylindrical wafer 1/2 inch in diameter and 1A inchlong. The pressures developed -against the slips were of the order ofseveral thousand pounds per square inch.

lFrom the `foregoing it will be seen that this invention provides lahighly eicient and positive anchor means for effectively anchoringvarious types of well tools against any movement in the well duringoperation of such tools.

AIt will be understood that various changes and modifications may bemade in the details of the illustrative embodiment within the scope ofthe appended claims without departing from the spirit of this invention.

What I claim and desire to secure by Letters Patent is:

1. An explosive-actuated anchor for well tools, comprising, a bodyattachable to a well tool to be anchored in a well, said body havinglongitudinally spaced upper and lower chambers and an -anchor sectionbetween said chambers, passageways extending through said anchor sectionproviding communication between said chambers, a flow-restrictingpassage defining the outlet `from said lower cham-ber, separate bodiesof explosive material in each of said chambers, means for igniting theexplosive material in the upper one of said chambers whereby to generatehigh pressure -gases which ow through said passageways and causeignition of the explosive materia-l in the lower chamber to therebygenerate additional high pressure gases, said how-restricting passagebeing operable to maintain high pressure of said gases in saidpassageways, and anchor means carrying wall-engaging elements mounted insaid anchor section for projection therefrom into anchoring engagementwith the well wall in response to the pressure of said gases in saidpassageways.

2. An explosive-actuated anchor for well tools according to claim -1wherein said explosive material is a deagrating-type explosive.

3. An explosive-actuated anchor for Well tools according to claim 1wherein said anchor means includes a plurality of radially disposedcylinders communicating at their inner ends with said passageways andextending to the exterior of the anchor section, and wall-grippinganchor elements slidable in said cylinders.

4. An explosive-actuated anchor for well tools according @to claim 1wherein said upper chamber is provided with an inlet pass-agecommunicating with its upper end, and inwardly-opening check valve meanscontrolling said inlet passage.

5. In combination with 'a well `tool actuatable by high iiuid pressure,an explosive-actuated anchor for said tool, comprising, -a bodyconnectible to said tool and insertable therewith into a well, said bodyhaving longitudinally spaced upper and lower chambers and an anchorsection between said chambers, passageways extending through said anchorsection providing communication between said chambers, a dow-restrictingpassage dehning the outlet from said lower chamber into said well tool,separate bodies of explosive material in each of said chambers, meansfor igniting the explosive material in the upper one of said chamberswhereby to generate high pressure gases which iiow through saidpassageways and cause ignition of the explosive material in the lowerchamber to thereby generate additional high pressure gases forsupplementing the pressure of the rst-generated gases, a portion of saidgases being concurrently discharged through said outlet to actuate saidwell tool, `and anchor means mounted in said anchor section forprojection therefrom into anchoring engagement with the well wall inresponse to the pressure of said gases in said passageways.

6. The combination of claim 5 wherein said well tool is a cutting toolemploying an incendiary chemical cutting agent.

7. The combination of claim 5 wherein said well tool is a perforator.

8. The combination of claim 5 wherein said explosive material is adeagrating-type explosive.

9. The combination of claim 5 wherein said anchor means includes aplurality of radially disposed cylinders communicating at their innerends with said passageways and extending to the exterior of the anchorsection, and wall-gripping anchor elements slidable in said cylinders.

10. The combination of claim 5 wherein the upper chamber is providedwith an inlet passage communicating with its upper end, andinwardly-opening check valve means controlling said inlet passage.

References. Cited, in. the le o this. patent UNITED srAfrEs PATENTS

